Hydraulic turbine



Patented Feb. 10, 1931 UNITED STATES PATENT OFFICE CLARK A. TERRY, OEGLENs PALLs, NEW YORK, AssIeNOR To INTERNATIONAL PAPER COMPANY, ACORPORATION OE NEW YORK HYDRAULIC TURBINE Application filed .Tune 27,

This invention relates to hydraulic turbines and aims to preventvibration due to the constant malring and breaking of the vacuum in thedraft tube and tail race,and tol increase the efciency of operation.

lt is well known to those familiar with the operation of hydraulicturbines, that there is a tendency of the water column to pulsate in thedraft tube, which is more or less pronounced according to the varyingconditions Y with respect to the changes in load, the action yof thegovernor, the sudden closing of the turbine gates, and other conditionsencountered in theypractical operation of the mech.-

The momentum of the water column in the draft tube under the conditionsmentioned, causes the column to break, and on the column being arrestedby the creation of the vacuum due to the break, the column is thrownupwardly again by the atmospheric pressure, and these actions beingrapidly repeated, result in violent pulsa-tions of the Water column,with the vacuum constantly making land breaking in the draft tube andtail race, and subjecting the mechanism to violent, injurious andannoying vibrations which greatly interfere with the eiciency ofoperation.

In accordance with the present invention this objectionable action ofthe turbine is prevented by the provision of means of improved form andconstruction which, on the tendency of the creation of avacuum in thedraft tube by the break ofthe water column, will act automatically toadmit air to the water column and thus check the creation of a vacuum Isuch as would bring about the objectionable actions above described.

In its more detailed form the invention consists of a suction reliefinstrumentality in the form of a valve applied in a passage leading fromthe outside atmosphere to the interior of the draft tube, which valve isspring pressed on its seat so as to prevent the escape of wateroutwardly from the draft tube under normal conditions of operation, butis capable when the force of the spring is overcome, to yield and openinwardly and thereby admit air to the draft tube, such opening movementof the valve being effect- 1925. Serial No. 39,904.

ed automatically when the suction of the water in the draft tube reachesa predetermined point.

The invention consists also in the provision of means for mullling the'action of the valve in itsv opening and closing movements, so as tosilence its operation to a minimum.

In the accompanying drawings:

Fig. lis a sectional elevation of a hydraulic turbine having myinvention applied thereto.

Fig. 2 is an elevation partly in section on an venlarged scale of theair admission valve mechanism. y

Fig. 3 is a cross section through the same on the line 3-3 of Fig. 2.

Referring to the drawings: v

l designates a hydraulic turbine provided as usual with the rotor 2carried by a rotor shaft 3, to which rotor water is admitted through theintake chamber l surrounding the rotor, and from which the water flowsdownwardly through a draft tube 5 and finds its'escape through a tailrace G.

7 designates a valve mechanism, which in accordance with my invention,is applied from the outside atmosphere and communicating with theinterior of the kdraft tube. The pipe 8 has its inner end exposed withinthe draft tube and extends through the wall thereof and has its outerend disposed in a lateral passage at the lower end of the inspection pit9 leading upwardly to the outside air through the masonry surroundingthe Vturbine'. The valve mechanism 7 comprises a valve casing 10connected at its inner end to the outer end` of the pipe 8 and connectedat its outer end to the inner'end of a cylindrical perforated shell 12.The valve casing is provided with a valve seat 13, against which seatsan inwardly opening valve lst carried by a valve stem l5 which is guidedat its inner end in a spider 16 fixed in the valve casing. llhek valvestem extends outwardly within the cylindrical shell 12 and through theouter end of the same and is acted on by a spring 17 surrounding theouter exposed end of the stem and bearing against the end of thecylindrical shell and against an adjustable head 18 on the end of thestem,

to the outer end of a passage or pipe 8 leading the tendency of thespring being to hold the valve yieldingly on its seat, and thereby closethe communication of the pipe 8 with the outside atmosphere.

The valve thus applied and held yieldingly to itsi'se'at bythe spring,will'p'revent the escape of Water "from the draft tube and is capable ofopening inwardly when the suction of the Water within the draft tubereaches a predetermined degree and the force of the spring is overcome,suoli inward opening of the valve permitting' air to flow 'inwardlythrough the perforated shell and pipe 8 and into the draft tube and thusacting to relieve 1 said abnormal suction. Under the normal 'opeationofl the turbine, with the water flowingdownwardly through the drafttube,the valve will be held closed by `its spring, thereby'iiiairtaining thatdegree of suction Vof the Water in 'the `draftV tubewhich is character is'ticof'tl'e iiormal action ofthe downwardlytlilvving"Yvater. Whenhowe'ver the conditions are such that the suctionof the water in- Icreases to an abnormal degree with a tendlsency ofthe'watercolumn to break and the *"creation'of a vacuum, the va lve will beopened autbriiaticallyagainst'the force of the spring by the atmosphericpressure, and air will be "admitted tothe draft tube and the" tendency130 of the column to breakl will be checked. In

this manner the valvewilly act to automatii 'allyprevent pulsations andvibrations of the water column, and while opening automati-V "ally 'toadmit air according to the degree of "`r`s'ctionl obtaining within thedraft'tube, it

i will under normal conditions of operation "prevent the escape of thewater from the draft tube and will maintain that degree of suction inthetube which is characteristic of the nor- Ao mal 'operation of theturbine.

' Inolrder to reduce the soundof the inrushing air on the opening/'ofthe valve and relieve the same-of undue noise,lmeans are provided tomuil'le the mechanism, which means 1n the @p present' case is inthe formof a mass 19 of curled hair or likeniaterial which is packed in` theperforated shell in the annular space between the same and an internalperforated '-tube 20' sustained centrally within the shell j fand5surrounding the valve stem. The mass of*`m`ziterial thus applied whilepermitting "the passage of the air through the perforated` shell andperforated tube and its entrance """into` the draft tube on the openingof the "55"valve', willeifectually silence the action of i' therapidlyllowing stream of air and Vwill at x. the' same time act tofilter the air. 'TheI improvedl mechanism constructed and appled'asabove described is positive and re` liable in action, is adapted forapplication to Jany form of draft tube, and is readily" i"adjustable soas to operL te under varying ydegrees of suction lwithin the tubeaccording to the'` varying conditions encountered in practice. Bypreventing the pulsations and vibrations ofthe water column, which arenot only annoying and disturbing in the plant but frequently of aninjurious and destructive character, the eiiiciency of the turbine isgreatly increased and safety in operation assured.

It'maybe desirable to apply to the pipe 8, a vacuum gage 2l, and toapply a gate valve 22 to the pipe between the gage and valve mechanism7, as shown in Fig. 2.

In the foregoing description and accom panying drawings I have set forthone form of embodiment of the invention by way of example, but it willbe manifest to the skilled mechanic that the details of the mechanismand its mode of application lma be variously changed-without departingIrom the spirit of the invention; and it will be understood that theinvention is not limited to any particular form or construction of theparts except in so far as such limitations are specified in the claims.

lIIa-ving thus described my invention, what I claim is l. In combinationwith a hydraulic turm90 inwardly opening valve and adjustable means' 595to control the opening of said valve, and responsive automaticallydirectly to a'predetern'iined degree of suction of the water therein toadmit air automatically to the water column when said degree of suctionisf?- vreached; whereby vibration of the Water column will be prevented.

` 2. In combination with a hydraulic turbine of the suction type havinga draft tube in which the water column submergesthe turbine rotor, anair inlet'mechanism associated with the draft tube and comprising aninwardly opening valve and adjustable means to control the opening ofsaid valve,and responsive'automatically directly to a predetermineddegree ofsuction of the water therein tol admit air automatically to thewater column when said degree of suction is reached, said valve whenclosed acting to prevent the escape of water through it.

3. In combination with a hydraulicturbine of thereaction type havinga'draft tube in which the water column submerges the tur* bine rotor, anair inlet valve applied to said draft'tube and an adjustablespringacting on said valve to hold it yieldingly closed, said valvelbeing constructed tojbe opened automatically by the suction of thewaterin said tube when saidsuction reaches a predetermined degree;whereby air will be admitted automatically to the wat-er column andvibrationV of the same will be' prevented.

In combination with a hydraulic turbine of the reaction type having adraft tube turbine rotor, a normally closed inwardl opening air inletValve applied to said dra tube, said valve being constructed to beautomatically opened and admit air to the draft tube When the suction ofthe Water n said tube reaches a predetermined degree, and adjustablemeans to control the opening of said Valve whereby the vibration of theWater column, and the escape of the Water through the valve, Will beprevented.

n testimony whereof, I have aiixed my signature hereto.

CLARK A. TERRY.

